1. Field of the Invention
The present invention relates to a phase adjustment device and a phase adjustment method for adjusting a phase (timing) of a pulse used when an image is obtained by a digital camera, and a digital camera in which the phase adjustment device is incorporated.
2. Description of the Related Art
In a digital camera, (digital still camera, digital video camera, mobile telephone provided with a camera, and the like), an analog imaging signal obtained by an imaging element such as CCD or an MOS sensor is converted into a digital imaging signal, and then, processed in a predetermined manner and recorded. In order to obtain an image of a photographic subject using the imaging element, a pulse for driving the imaging element, a pulse for detecting a signal level, and the like, are necessary, and it is difficult to adjust phases of these pulses in the hardware designing stage due to variability generated in the manufacturing process. Therefore, the phases are adjusted by a technician after the manufacturing process, and information showing the adjusted phases is stored in a memory region and read from the memory region when the product is actually used so that the phases are optimally set.
There is a known conventional technology wherein only a noise element is fetched in a minimum exposure time, and the phase is adjusted under such a condition that a high-frequency component (noise element) is minimized. An example of the technology is recited in No. 2005-151081 of the Japanese Patent Applications Laid-Open.
In the field of the digital camera, various changes may be made to a system where a phase adjustment device is incorporated. In the case where the digital camera is adopted as a hospital-use camera, it is possible to exchange the imaging element after the digital camera is manufactured. In the case where the system provided with the digital camera or the imaging element is thus subjected to some change, the phase of the pulse which drives the changed component is naturally different, which makes it necessary to readjust the phase. However, it is difficult to speedily and easily change the system or replace the imaging element when a technician manually readjusts the phase.
In the Document mentioned above, a characteristic of each pulse is disregarded though the pulses to be adjusted range in a plurality of types, and it is demanded that the phases of all of the pulses be optimized in the same method. Therefore, it is not possible to expect a high accuracy in the phase adjustment.